1. Technical Field
The present invention relates to an image forming device having a feed route to feed a recording medium from a feed tray to a transfer route and forming an image on the recording medium transferred on the transfer route.
2. Background Arts
An inkjet image forming device adopts a mechanism which disposes a registration roller at the upstream of an image former on a transfer route, temporarily holds a recording medium supplied from a scraper roller and a pickup roller configured to transfer a recording medium stacked on a feed tray one by one, and adjusts a timing to send out the recording medium to the transfer route. Further, in such an image forming device, a large-capacity feed unit in which a number of recording media are stacked is installed in an attachable/detachable manner, or is incorporated in equipment in order to perform printing processing of a large number of recording media of equal size.
In this large-capacity feed unit, it is necessary to secure a maintenance space, such as a space for eliminating a paper jam on the feed route, and thus a plurality of intermediate transfer rollers is disposed between the pickup roller and the registration roller in order to secure to some extent the distance from the pickup roller to the registration roller and also to stably transfer recording media of various sizes.
In the image forming device described in Japanese Patent Application Laid-Open No. 2000-327150, an intermediate transfer roller is driven by an electromagnetic clutch driven by the action of an electromagnetic force using an electromagnet or a one-way clutch that transmits a rotational force only in one direction. In the case where such an electromagnetic clutch or one-way clutch is used, when the registration roller provided at the downstream side nips a recording medium, the drive of the intermediate transfer roller is brought into the off state and after that, by causing the intermediate transfer roller to rotate idly (so-called “accompanying rotational motion”) in accordance with the sheet transfer by the registration roller, the recording medium is prevented from traveling in the opposite direction of the transfer direction toward the upstream.